Connection systems are used to connect electrical cables, optical cables, hydraulic lines or other flexible cables between first and second end points that are able to rotate with respect to one another. Typically, a flexible cable is carried within a reverse bend radius chain that supports and guides the cable whilst the end points rotate with respect to one another. Such reverse bend radius chains enable rotation of greater than 360 degrees to be achieved. However, such chain based systems are designed to operate in a single plane, and are not able to deal with linear movement of the end points out of that plane of operation. Some example rotary reverse bend radius chains are produced by IGUS GMBH.
An example of dealing with relative linear movement of the end points is illustrated in FIG. 1 of the accompanying drawings. A connector system 1 has a first connector 2 and a second connector 4, and is provided within a housing 10. The second connector 4 is mounted on a connector carrier 6 which itself is mounted on a shaft 8. The shaft 8, and hence connector carrier 6, is mounted for rotational movement R and linear movement L, with respect to the housing and first connector 2. A flexible cable 12 is provided to connect the first connector 2 to the second connector 4. As the shaft 8 moves linearly within the housing 10, the cable 12 curls and uncurls within the housing to enable the connection to be maintained. As the shaft rotates, the cable 12 then curls around the shaft 8. However, such a system is prone to cable snagging, and over bending.
In particular, the system of FIG. 1 is not suitable for subsea applications, for example, for a water stream power generating device such as that shown in FIG. 2. Such a device 14 comprises a turbine unit 15 mounted on the seabed 16 on a support structure 17. An engagement system 18 is provided that enables the turbine unit 15 to be attached releasably to the support structure 17. In the example shown in FIG. 2, the turbine unit 15 is rotatable about a vertical axis with respect to the support structure 17, and so electrical and/or hydraulic and/or control connections between the turbine unit 15 and the support structure 17 must be able to deal with rotation of the turbine unit 15. In addition, the turbine unit 15 is releasably engagable with the support structure 17, such that the unit 15 may be removed along the vertical axis from the support structure 17. The connections between the unit 15 and the support structure 17 can be made after the unit has been located on the support structure. In such a case, the connectors must be able to move axially within the engagement system, whilst maintaining the ability to rotate within the engagement system. In one example, the unit 15 is located on the support structure 17, and the connectors are rotated for polar alignment. The connectors are then moved axially towards the support structure to engage with corresponding connectors therein. The connection system then is able to allow the unit 15 to rotate with respect to the support structure. It will be appreciated that the connector alignment and engagement system may be provided on the support structure, or split appropriately between the support structure 17 and the unit 15 Thus, it is desirable to provide a connection system to enable electrical, hydraulic, optical, control and/or other connections to be made between the turbine unit 15 and the support structure 17, whilst allowing for rotation and linear movement of the connectors within the engagement system.